The present invention relates to a karaoke circuit for optical disk players, and more particularly to a karaoke circuit with improved sound quality and simplified circuitry.
Generally, an optical disk player (laser disk player) records a signal on a disk in digital form, projects coherent light such as a laser beam onto the disk's surface, and receives reflected light, so as to reproduce information according to the variations in the intensity of the reflected light.
Recently, an optical player was developed incorporating a karaoke circuit which outputs a mixed music/vocal signal (a musical accompaniment audio signal and a voice-over audio signal), besides simply playing music (the music signal).
Meanwhile, the optical disk player outputs signals corresponding to respective channels according to disk type, as shown in TABLE 1.
TABLE 1 ______________________________________ recorded format music by channels disk type recording method L-channel R-channel ______________________________________ CD digital stero signal stero signal general LD analog stero signal stero signal digital stero signal stero signal analog analog mono vocal + mono multivoice accompaniment accompaniment LD hi-fi analog mono vocal + mono multivoice accompaniment accompaniment LD digital stero stero accompaniment accompaniment ______________________________________
If the utilized disk is a compact disk (CD), stereo signals are output through the left and right channels and the music recording method is digital. Here, CDs are divided into two types, in one of which only music is loaded (i.e., a classical music CD) and in the other of which the music and a vocal signal are loaded together (i.e., a popular music CD). In the latter type CD, a stereo signal mixed with a vocal signal is transmitted to the left and right channels. If the disk is an analog multivoice laser disk (LD), the music recording method is analog, and mono accompaniment (i.e., instrumental music without vocals) is output through the left channel and a vocal signal mixed with mono accompaniment is output through the right channel.
If the disk is a hi-fi multivoice LD, since the music recording method is both analog and digital, when the analog recording method is selected as the output mode, mono accompaniment is output through the left channel and mono accompaniment and a vocal signal are output through the right channel, and when the digital recording method is selected, stereo accompaniment signals (i.e., instrumental music without vocals) are output through the left and right channels.
Here, the CD is a disk in which only audio signals are loaded and the LD is a disk in which both an audio signal and possibly a video signal are loaded. The term "multivoice" indicates that different signals are loaded in the left and right channels; for instance, mono accompaniment is loaded in the left channel while vocal signal and mono accompaniment are loaded in the right channel. In a hi-fi multivoice LD, as shown in TABLE 1, data is recorded in two forms (analog and digital).
Accordingly, with respective channels for the various disks, the conventional optical disk player has a complicated circuitry which increases the production cost. Additionally, if the disk type is the hi-fi multivoice LD, since the output is generated according to the selected recording method (analog or digital), in the case of a karaoke mode, a mixed signal of analog mono accompaniment and vocal signal from the right channel is output through a speaker, which reduces the sound quality.